Water mites are among the most diverse and abundant groups of benthic macroinvertebrates in the world. With more than 7,500 described species, water mites are known to occur in nearly every known lentic and lotic freshwater environment. In addition, water mites occupy an unusual niche within benthic macroinvertebrate communities as their larvae are parasitic on various invertebrates as hosts. However, despite their relative diversity, abundance, and trophic position, water mites are widely neglected in aquatic biomonitoring assessments. In fact, in most bioassessment protocols water mites are either ignored completely or identified collectively as "Hydrachnidia" or "Hydracarjna", an artificial grouping of several water mite superfamilies. Constraints that may contribute to this widespread neglect include knowledge gaps in basic water mite biology, taxonomy, distribution, and conceptions that water mites are difficult to sample and identify. During this project, I aim to fill these knowledge gaps by identifying lotic water mite communities in central Pennsylvania and determine if and how these assemblages reflect water quality conditions. By sampling 26 sites along polluted and unpolluted, high-quality streams and collecting over 5,000 individual benthic macroinvertebrates and nearly 15,000 water mites, I 1) develop a standardized, quantitative sampling scheme for water mites for biomonitoring purposes, 2) inventory lotic water mite taxa in central Pennsylvania, 3) compare water mite community changes between polluted and unpolluted streams, and 4) document seasonal changes in water mite assemblages. By completing these objectives, I expand our understanding of this unique group of animals and build support for including them in future bioassessment studies.